PyBitmessage-2021-04-27/src/network/socks5.py

"""
src/network/socks5.py
=====================

"""
# pylint: disable=attribute-defined-outside-init

import socket
import struct

from proxy import GeneralProxyError, Proxy, ProxyError


class Socks5AuthError(ProxyError):
    """Rised when the socks5 protocol encounters an authentication error"""
    errorCodes = (
        "Succeeded",
        "Authentication is required",
        "All offered authentication methods were rejected",
        "Unknown username or invalid password",
        "Unknown error"
    )


class Socks5Error(ProxyError):
    """Rised when socks5 protocol encounters an error"""
    errorCodes = (
        "Succeeded",
        "General SOCKS server failure",
        "Connection not allowed by ruleset",
        "Network unreachable",
        "Host unreachable",
        "Connection refused",
        "TTL expired",
        "Command not supported",
        "Address type not supported",
        "Unknown error"
    )


class Socks5(Proxy):
    """A socks5 proxy base class"""
    def __init__(self, address=None):
        Proxy.__init__(self, address)
        self.ipaddr = None
        self.destport = address[1]

    def state_init(self):
        """Protocol initialization (before connection is established)"""
        if self._auth:
            self.append_write_buf(struct.pack('BBBB', 0x05, 0x02, 0x00, 0x02))
        else:
            self.append_write_buf(struct.pack('BBB', 0x05, 0x01, 0x00))
        self.set_state("auth_1", length=0, expectBytes=2)
        return True

    def state_auth_1(self):
        """Perform authentication if peer is requesting it."""
        ret = struct.unpack('BB', self.read_buf[:2])
        if ret[0] != 5:
            # general error
            raise GeneralProxyError(1)
        elif ret[1] == 0:
            # no auth required
            self.set_state("auth_done", length=2)
        elif ret[1] == 2:
            # username/password
            self.append_write_buf(
                struct.pack(
                    'BB', 1, len(self._auth[0])) + self._auth[0] + struct.pack(
                        'B', len(self._auth[1])) + self._auth[1])
            self.set_state("auth_needed", length=2, expectBytes=2)
        else:
            if ret[1] == 0xff:
                # auth error
                raise Socks5AuthError(2)
            else:
                # other error
                raise GeneralProxyError(1)
        return True

    def state_auth_needed(self):
        """Handle response to authentication attempt"""
        ret = struct.unpack('BB', self.read_buf[0:2])
        if ret[0] != 1:
            # general error
            raise GeneralProxyError(1)
        if ret[1] != 0:
            # auth error
            raise Socks5AuthError(3)
        # all ok
        self.set_state("auth_done", length=2)
        return True

    def state_pre_connect(self):
        """Handle feedback from socks5 while it is connecting on our behalf."""
        # Get the response
        if self.read_buf[0:1] != chr(0x05).encode():
            self.close()
            raise GeneralProxyError(1)
        elif self.read_buf[1:2] != chr(0x00).encode():
            # Connection failed
            self.close()
            if ord(self.read_buf[1:2]) <= 8:
                raise Socks5Error(ord(self.read_buf[1:2]))
            else:
                raise Socks5Error(9)
        # Get the bound address/port
        elif self.read_buf[3:4] == chr(0x01).encode():
            self.set_state("proxy_addr_1", length=4, expectBytes=4)
        elif self.read_buf[3:4] == chr(0x03).encode():
            self.set_state("proxy_addr_2_1", length=4, expectBytes=1)
        else:
            self.close()
            raise GeneralProxyError(1)
        return True

    def state_proxy_addr_1(self):
        """Handle IPv4 address returned for peer"""
        self.boundaddr = self.read_buf[0:4]
        self.set_state("proxy_port", length=4, expectBytes=2)
        return True

    def state_proxy_addr_2_1(self):
        """
        Handle other addresses than IPv4 returned for peer
        (e.g. IPv6, onion, ...). This is part 1 which retrieves the
        length of the data.
        """
        self.address_length = ord(self.read_buf[0:1])
        self.set_state(
            "proxy_addr_2_2", length=1, expectBytes=self.address_length)
        return True

    def state_proxy_addr_2_2(self):
        """
        Handle other addresses than IPv4 returned for peer
        (e.g. IPv6, onion, ...). This is part 2 which retrieves the data.
        """
        self.boundaddr = self.read_buf[0:self.address_length]
        self.set_state("proxy_port", length=self.address_length, expectBytes=2)
        return True

    def state_proxy_port(self):
        """Handle peer's port being returned."""
        self.boundport = struct.unpack(">H", self.read_buf[0:2])[0]
        self.__proxysockname = (self.boundaddr, self.boundport)
        if self.ipaddr is not None:
            self.__proxypeername = (
                socket.inet_ntoa(self.ipaddr), self.destination[1])
        else:
            self.__proxypeername = (self.destination[0], self.destport)
        self.set_state("proxy_handshake_done", length=2)
        return True

    def proxy_sock_name(self):
        """Handle return value when using SOCKS5 for DNS resolving instead of connecting."""
        return socket.inet_ntoa(self.__proxysockname[0])


class Socks5Connection(Socks5):
    """Child socks5 class used for making outbound connections."""
    def __init__(self, address):
        Socks5.__init__(self, address=address)

    def state_auth_done(self):
        """Request connection to be made"""
        # Now we can request the actual connection
        self.append_write_buf(struct.pack('BBB', 0x05, 0x01, 0x00))
        # If the given destination address is an IP address, we'll
        # use the IPv4 address request even if remote resolving was specified.
        try:
            self.ipaddr = socket.inet_aton(self.destination[0])
            self.append_write_buf(chr(0x01).encode() + self.ipaddr)
        except socket.error:
            # Well it's not an IP number,  so it's probably a DNS name.
            if Proxy._remote_dns:  # pylint: disable=protected-access
                # Resolve remotely
                self.ipaddr = None
                self.append_write_buf(chr(0x03).encode() + chr(
                    len(self.destination[0])).encode() + self.destination[0])
            else:
                # Resolve locally
                self.ipaddr = socket.inet_aton(
                    socket.gethostbyname(self.destination[0]))
                self.append_write_buf(chr(0x01).encode() + self.ipaddr)
        self.append_write_buf(struct.pack(">H", self.destination[1]))
        self.set_state("pre_connect", length=0, expectBytes=4)
        return True

    def state_pre_connect(self):
        """Tell socks5 to initiate a connection"""
        try:
            return Socks5.state_pre_connect(self)
        except Socks5Error as e:
            self.close_reason = e.message
            self.set_state("close")


class Socks5Resolver(Socks5):
    """DNS resolver class using socks5"""
    def __init__(self, host):
        self.host = host
        self.port = 8444
        Socks5.__init__(self, address=(self.host, self.port))

    def state_auth_done(self):
        """Perform resolving"""
        # Now we can request the actual connection
        self.append_write_buf(struct.pack('BBB', 0x05, 0xF0, 0x00))
        self.append_write_buf(chr(0x03).encode() + chr(
            len(self.host)).encode() + str(self.host))
        self.append_write_buf(struct.pack(">H", self.port))
        self.set_state("pre_connect", length=0, expectBytes=4)
        return True

    def resolved(self):
        """
        Resolving is done, process the return value.
        To use this within PyBitmessage, a callback needs to be
        implemented which hasn't been done yet.
        """
        print "Resolved %s as %s" % (self.host, self.proxy_sock_name())